Process of treating cracked hydrocarbon vapors



July 30, 1935. G. EGLOFF 2,009,879

PROCESS OF TREATING CRACKED HYDROCARBON VAPORS Filed March 22, 1930 /4A9 0 y 6 /Z 7 HTTOR/V J Patented July 3Q W35 UNETE srr s aware arr FFEQEPEEQCESS (PF TREATHNG CRAQKIED HYDRCARBN VURS tion of South DakotaApplication March 22, 1930, Serial No. 437,975

' 6 Claims. (Cl. 196-36) This invention relates to a process of treatingcracked hydrocarbon vapors and pertains in its specific embodiment tothe treatment of cracked hydrocarbon vapors, subjecting them to theaction of zinc chloride preferably in aqueous solution and preferablywith the use of activated or atomic hydrogen for the purpose ofproducing stable, water-white, sweet motor fuel having low sulphur andgum content.

It is among the objects of my invention. to bring about thedesulphurization of the cracked hydrocarbon product so that subsequentrefining for sulphur reduction and sweetening, together with the expenseand losses involved, are re- 31 duced to a minimum or are entirelyeliminated.

Desulphurization of the product causes a reduction or minimizing ofcorrosion in the plant equipment and in the automotive equipment wherethe motor fuel is consumed.

Frequently when finished gasolines are stored, especially crackedgasolines, chemical changes occur which affect the color, gum contentand anti-knock properties. These properties are affected particularly bylight and the oxygen of the air which promote the undesirable reactionswhich bring about the above changes. Although the chemistry of thesechanges is not thoroughly understood, it is evident that the presenceof.

certain highly reactive hydrocarbons, for example, those related todiolefine's, terpenes, etc., are involved in the undesired reactions. Itis one of the chief objects of my invention to hydrogenate theseunsaturated hydrocarbons, converting them to stable motor fuelhydrocarbons and avoiding a decreased yield of the motor fuel product.It is not thepurpose in carrying out the process of the invention tocompletely saturate all the unsaturated hydrocarbons present in thecracked low boiling product for olefine lay- 40 drocarbons in generalare very stable and possess good anti-knock properties. The purpose israther to add hydrogen in regulated amounts to the highly unsaturatedhydrocarbons referred to above for the purpose of improving theantiknock properties of motor fuel hydrocarbons 45 present in thecracked product, reducing and min imizing subsequent refining such assulphuric.

acid treatment, and the stabilization of the final .motor fuel product.

The practice of my invention in addition to producing ahydrocarbonproduct of good color and low gum content brings about thestabilization of this product so that it will not readilygo off color.The formation of color in gaso- 55 lines is not only undesirable from amarketing viewpoint (a colorless gasoline can be more readily dispensedthan a yellowish gasoline when using visible bowls), but is usually alsoan index of the formation of gum-like, polymerized material whichaffects the operation of the motor as is evidenced by the clogging offeed lines, in-' terference with the proper operation of the carburetorand the sticking of the valves in the motor.

The anti-knock property of a motor fuel is one of its most important andvaluable characteristics. The higher the anti-knock value or knockrating of a motor fuel, the greater is its efficiency. A change in thisvalue during storage is, therefore, a disturbing factor since adesirable motor fuel may change to such an extent that it will requiresome form of treatment to restore it to its original market value. Theaddition of anti-knock materials, the use of inhibiting agents, blendingwith exceptionally high anti-knock motor fuel stocks, or repetition ofprevious treatment are methods used to prevent reduction of anti-knockvalue of motor fuel oil in storage or to restore the antiknock value ifit has fallen off. The use of my process minimizes or eliminates the useof these preventative and restoration methods and eliminates all of theuncertainties involved.

In the practice of my invention, I use zinc chloride to promote in partthe results that I have referred to above. Although I may use the zincchloride in solid form or may distribute the zinc chloride on adistributing agency so as to allow a large reaction surface, Ipreferably use an aqueous solution which may be maintained at any givenstrength during the process by addition of this salt or by the additionof water. The zinc chloride solution reacts with the deleteriouscolorforming substances, including some of the sulride. Activatedhydrogen may be used as such or in the form of activatedhydrogen-containing gases such as coal gas, oil gas, water gas, producergas, natural gaacracked gas, etc. The activated hydrogen orhydrogen-containing gases are preferably introduced into the zincchloride solution and together with the zinc chloride solution bringsabout the results above enumerated.

In carrying out the process of my invention, I do not wish to limitmyself to the apparatus in which it is used since the invention can verywell be carried out as a step within the cracking process comprisingheating and reaction zones with provisions for returning partiallyconverted products for retreatment, together with condensing, coolingand collecting means as well as in separate equipment which wouldinvolve vaporizing, processing, condensing, cooling and collectingmeans. Preferably, however, the process is carried out as a step in thecracking process, treating the cracked hydrocarbon vapors after leavingthe dcphlegmator, as will be hereinafter described.

The accompanying drawing, given only for the purpose of more clearlyillustrating my invention, is a diagrammatic view, not drawn to scale,of one of the forms of apparatus in which my invention may be practiced.

Referring to the drawing, cracked vapors, preferably coming directlyfrom the dephlegmator of a cracking plant, may be introduced throughline I and valve 2 into treater tank 3.

A solution of zinc chloride in water may be supplied through line 4 andvalve 5 to pump 6 and thence fed into the treater tank 3 through line I,valve 3 and line I. Additional water may also be fed into tank 3 and issupplied, in this case, through line l0 and valve II to pump I2 whichfeeds it through line l3 and valve l4 into tank 3. A solution of zincchloride in water may be maintained within tank 3, the level of thesolution in the tank being maintained fairly constant. This liquid levelmay be indicated in a gauge glass 9 attached to the tank. Theintroduction of zinc chloride and water into tank 3 may be continuous orintermittent and may be in such proportions that the strength of thesolution within tank 3 is maintained substantially uniform.

The cracked vapors are intimately contacted with the solution of zincchloride in tank 3. being introduced below the liquid level within thetank and bubbling up through the solution to the vapor space above theliquid.

Activated or atomic hydrogen may also be introduced into the zincchloride solution in tank 3. The hydrogen is, in this case, suppliedthrough line l5 and valve IE to pump I? and fed therefrom into tank 3through line 18 and valve Hi. The introduction of activated or atomichydrogen may be simultaneous with the introduction of cracked vapors.

That portion of the cracked vapors which is condensed in tank 3 may becollected upon the surface of the aqueous solution of zinc chloridetherein and may be withdrawn through line 20 and valve 2| to tower 22which may be any suitable form of flash distilling and fractionatingdevice such as a tower containing perforated pans, packing, bubble traysor the like.

Tower 22 is preferably maintained under a lower pressure than thatemployed in treating tank'3, and the latent heat liberated by thereduction in the pressure imposed upon the liquid may serve to vaporizesubstantially all of this liquid introduced into tower 22. That portionof the liquid introduced into tower 22 which remains unvaporized,together with condensate from vapors which are condensed in tower 22,may be removed through line 23 controlled by valve 24.

Vapors from tower 22 may pass through line 25 and valve 26 into line 21.Vapors from treater tank 3 may also pass through line 21 and valve 23and, together with the vapors introduced into line 21 from tower 22, maypass through valve 23 to be subjected to condensation and cooling incondenser 30, thereafter passing through line 3| and valve 32 intoreceiver 33.

Uncondensed gas may be released from receiver 33 through line 34controlled by valve 35, and the distillate collected in receiver 33 maybe withdrawn through line 36 and valve 31.

Treater tank 3 is preferably operated at superatmospheric pressure,which pressure may be the same or may be substantially higher orsubstantially lower than the pressure employed in the cracking unit inconjunction with which the treating process may be operated.Substantially atmospheric or sub-atmospheric pressures may, however, beemployed, if desired, in treater tank 3. Preferably a pressuresubstantially reduced below the pressure employed in treater tank 3 ismaintained in fractionating tower 22 as well as the condensing andreceiving equipment.- The process may, however, be operated withsubstantially equalized pressure throughout.

As an illustration of the application of the invention and the resultsobtained when processing the cracked vapors boiling below 495 F. andoriginating from a Mexican gas oil, the cracked vapors are directed tothe chamber 3 containing an solution of zinc chloride. The temperatureof these vapors as they enter the chamber is approximately 510 F., andthe pressure approximately 220 pounds per square inch. The vapors areintimately mixed with the activated hydrogen introduced as they bubblethrough the zinc chloride solution and are condensed in part as they arereacted upon by the zinc chloride solution. Approximately 40% remainuncondensed and pass over to the condenser and receiver, the pressurebeing released from approximately 215 pounds to 30 pounds pressure bymeans of valve 28. The oil layer formed on top of the zinc chloridesolution in chamber 3 is withdrawn through line 20 where the pressure isreleased by valve 2| to approximately 40 pounds and the oil flashdistilled by its self-contained heat in the tower 22. Approximately 15%of the total vapors introduced .into the process are withdrawn ascondensate through line 23, the fractionated vapors passing overhead tothe condenser and receiver and mix ing with the product from chamber 3.The motor fuel withdrawn from the receiver 33 has an endpoint ofapproinmately 420 F., is stable and water-white, the sulphur contentbeing approximately .12%.

I claim as my invention:

1. A process of treating cracked hydrocarbon vapors, which comprisespassing the vapors while still hot into contact with a water solution ofzinc chloride in the presence of added hydrogen while undersuper-atmospheric pressure adequate to effect substantial separation ofunsaturates contained in the cracked vapors, separately drawing of! thecondensate and the uncondensed vapors after said treatment, subjectingthe condensate to further distillation at reduced pressures, andcollecting the vapors from said last mentioned distillation.

2. A method of refining mineral oils which consists in cracking the oilto form a cracked vapor, adding hydrogen to the vapor, naming the heatedvapor and added hydrogen through or in contact with a maintained aqueoussolution of zinc chloride under temperature and pressure conditionsadequate to effect substantial saturation of unsaturates contained inthe cracked vapor, and then condensing the vapors.

3. A method for refining cracked gasoline 7i vapors containing olefinhydrocarbons and highly reactive unsaturates such as diolefins andterpenes, said method comprising reacting the vapors with added hydrogenin the presence of an aqueous solution of zinc chloride undertemperature and pressure conditions adequate to hydrogenate saidunsaturates' without'substantially saturating said olefin hydrocarbons.

4. A method for refining cracked gasoline vapors containing olefinhydrocarbons and highly reactive unsaturates such as diolefins andterpenes, said method comprising reacting the vapors with added hydrogenin the presence of a maintained. aqueous solution of zinc chloride undertemperature and pressure conditions adequate to hydrogenate saidunsaturates without substantially saturating said olefin hydrocarbons.

5. A process for refining cracked hydrocarbon vapors which comprisesadding hydrogen to the vapors and subjecting the resultant mixture inthe presence of an aqueous solution of a zinc salt to temperature andpressure conditions adequate to effect substantial saturation ofunsaturated hydrocarbons contained in the cracked vapors.

6. A process for refining cracked hydrocarbon I vapors which comprisesadding hydrogen to the vapors and subjecting the resultant mixture inthe presence of an aqueous solution of zinc chloride to temperature andpressure conditions adequate to efiect substantial saturation ofunsaturated hydrocarbons contained in the cracked g vapors.

I GUSTAV EGLOFF.

